Treatment of alumina containing catalytic composites



Patented Sept. 8, 1953 2,'651,61-7.. TREATMENTOF'ALUMINK CONTAININGCATAIiYTIO COMPOSITES LouisrSchmerling; kiverside lll zassignontc-Unimversal Oil: Products Co mpany; Ghioago,-,.llll. acorporationoflDelawai-e NbDta-wing; Application Ann -H3319,

Serial No. 88;053i3 (Ola-252MB),

This invention relates to ythe treatment of alumina-containingcomposites-for the" purpose of; enhancing :the' catalytic: propertiesthereof. in hydrocarbon: conversion reactions effected? in--,thepresence. Ofs-SllGh composites. More:specifical-ly; the: invention;concerns; the: treatmentv of such catalystslwith"an-acidicreagentv atspecified conditions; to: formx. therebyra; resulting: composite having:greater." activity' and/or a; reduced tend;- ency; toform undesirableby-products asecharacteristicrof the initial ;,untreated composites;

It is widely recognized that. certain ressentiallymineral?composites-containingalumina; such as the variousiclayszandsyntheticgcompiosites ofvalue min'ai and silica or! alumina and: other:refractory metal oxides are catalytically: activesinpromoting certainhydrocarbon;conversionzrreactions; as: for example, the catalyticcracking: of? petroleum fractions to form hydrocarbons;of:lowe1tmolecuslar'wei'ght boilingirr the gasoline range; the poly-'- merization ofaliphatic un'saturatediv hydrocar; cons to converthighly volatilecharging stockssto hydrocarbons that: arerliquidiat normal cndi+ tions,etc; It. is further: recognized: that:.upon continued-:usea ofsuchaluminaecontainingz com:- posites, their:activity.generallytdeclinesiiandtthe partially inactivatedcatalystsrfosten side reacttions; many oflwhich are consideredzundesira'ble in thatithey result:inzthezproductiomofi materials havingP a- IESSEIZTdGgIEfi f: HtlIitYithfiZIifbhBldBSil'Bd product:.. Assatypicalzexample; the ccnti-nuediuse of. silica-aluminacompositescofi'eitlier synthetic or natural origin; inihydrocarboncracking:;proc:- esses graduallyyreduces, thesactivityofirltheicatarlystL for effecting;- the desirediproductiomof;gassilineboiling range. hydrocarbonsras;theiresultsof carbon deposition on'thecatalys-ti andi usually/the undesirable production; of-vmethanaycarbonr-and hydrogen simultaneously increases.:.due to;deep:;-seated Icracking reactions, thus accounting; for: a two-foldreductionin-:. yield; of:. thesdesiredwgasoe line product by virtue.ofitheloweryieldiper pass and. greater consumption"; of the charging:stock to form the undesired carbon; hydrogen: and methane: products;Furthermore;. the: ratio of hydrogen to; methane: producedi increases"vas the catalyst decreases-in activity; Liliewise intmany instances; afreshly prepared: catalyst: composite may: result in excessive:-production of: theiundee sired: hydrocarbon: degradation? productseither because ofithe:pr.esen'ce of foreigniconstituentsiin thecomposite; or:becauseiofi'its rinherentrpropeita tiesa Qne. of the:primary; ObjB'GtSOfFthGl present process: to veffectiimprovement inxthescatalytic propertieszof an: alumina-containinrgc;v composite,

particularly fore hydrocarbom conversion reactions.-,

Anotherobject-ofrthe invention is to provide a method of; treating;aluminaecontaining; catalytic composites-.toreducetheir tendencytovformundesirable byg-products of: hydrocarbon conversion reaotionsa;Still-another: object; of the invention 15 .7130 provide: a methodfor.-reactivating; a spent hydrocarbon conversionicatalyst or toiactivate'anotherwise relatively;-inac.ti;ve composite.

In: onerofl itsvembodiments therpresenti invene tlQIhGOIlOBIIlS a;prooessrwhichicomprises treating an:.alumina-containing;compositawith; areagent comprisinggani organicacidqhaving a: dissociationconstant-lessvthan L 1i0 at-ireactionaconditions sufiicientto convertgarti least-ia portion of the aluminai-conta-inediing said; composite toarbasic. aluminumz salt; 013 said; acidyancl, thereafter; treatingthe:compositeiwithiwater -attc onditions. sufficient to efiecthydrolysis of the resulting aluminum salts 1 In: accordancejwithanotherembodiment ofzthe invention;- a=:process for: activating; analuminametal-koxidezcomposite:catalystzis provided whichcomprisesztreating thescatalyst with an; aqueous organic:acidycontainingiat least by: weight of acida said acidshaying adissociation constant of; less than-= 1= 1 0 at: a temperature; of! fromabout'il50-f:to aboutz3ufiirci and/atapressuresufficient to rmaintain isaid? :acid: in substantially liquimphazsepand thereafterireactingtheresulting treated'icatalyst: composite-with: Waterwatatemperatureaaboverabout 100? and: at a pressure sufficient tomaintainssaid .watenin substantially liquid phase;- ,7.

ALmore-aspecific: embodiment: of: the; inventionrelates:'to:a:process-dorcreactivating a spenti silica."-alumina:crackingg'catalystwhich ;comprises-:heat+ing-jsaidr-spent;icatalystwith an; acidr'containinge a majorspropjortionof; aceticsacid and iauminorrproxportion; ofivhydrochloriczacid?atz-astemperatureiof from-about 200 to2about1 250fi C., recovering. theresulting; treated: catalyst, reacting. said vtreated catazlystwithzwatrtatxaitemperature in :excess of aboutl15'03=-(liandiataipressureisufficient to maintainzssaid wat'err-ini'substantially: liquid phase, thereafter; drying said catalyst't and?heating the same; ate a.:. temperature ofzi from"; about 350. to aboutwuQtherobjectsand embodiinentsof 'the present process concerning;specific: factors involved in the; invention will be: hereinafterreferred t'o' in greater: detaib im the; following furtheri descriptionsofttlieszinventionn Thea ali'zminai-containing: composites: which(nearly pure alumina) montmorillonite, ben-ifj tonite, etc., or asynthetically produced composite such as an alumina-silica,alumina-chromia, alumina-zirconia, or other of the many aluminametaloxide composites commonly employed as catalysts for specifichydrocarbon-conversion reactions. Aside from its use in activating thealumina-containing composite for catalytic hydrocarbon conversionreactions, the present acidic reagent may also be utilized for thepurpose of modifying the physical properties of'the composite to betreated; such as reducing its density by removal of a portion of thealumina contained in the original composite to provide a porousparticle. The composite as originally formed in many instances maycontain foreign components, such as one or more metallic oxides whichmay adversely affect the catalytic properties for which the catalyst maybe initially in tended and which are desirably removed to provide acatalyst possessing optimum catalytic properties. Typical instances ofsuch materials are catalytic composites prepared from impure aluminaores which may contain such foreign components as the oxides or salts ofcalcium, sodium, iron, or other metals. In the case of such composites,the method of treatment provided herein may be applied for the specificpurpose of removing the foreign components while concurrently enhancingthe catalytic properties of the composite or modifying its physicalproperties. 7

A class of alumina-containing composites, especially adapted fortreatment by the present process, comprises spent alumina-containingcatalysts which have become deactivated by con tinuous use of thecatalyst in a hydrocarbon conversion process. The present treatmentwhich includes heating the composite in the presence of an organic acidhaving a dissociation constant less than 1 10 presumably converts thealumina in contact with the reagent to a salt of the acid (at thetemperature conditions and utilizing the concentration of acid hereinspecified) and the subsequent hydrolytic treatment of the acid-treatedcomposite with water at a relatively high temperature hydrolyzes thealuminum salt to form a porous, reactivated form of aluminum oxide,primarily on the surface of the particle which will subsequently comeinto contact with the hydrocarbon charging stock in the conversionprocess involving the catalyst. The calcination of the treated compositeserves to fix the reactivated alumina to the body of the particle and/orbring it into chemical association with other components of thecatalytic composite. When utilizing a deactivated catalyst as thematerial subjected to treatment herein, it is desirable to remove asmuch as possible of the carbonaceous material, if any, deposited thereonprior to the present treatment, as for. ex-

ample, by heating the deactivated composite in an oxygen-containingatmosphere and at a temperature sufficient to oxidize the deposit fromthe catalyst. It is frequently noted in carrying out such a procedurethat the treated catalyst may exhibit an activity greater than theoriginal 4 catalyst prior to use and/or may have other advantageousproperties, such as a lower density, developed by the present method oftreatment.

The acid treating reagent of the present process is an organic acidcapable of reacting with aluminato form a basic salt of aluminum at thereaction conditions provided herein or a mixture of such acid with amineral acid containing a minor amount of the latter acid. The organicacid is utilized in a relatively concentrated form,

containing at least 60 percent by weight of the acid, and when utilizedin the treating reagent,

the mineral acid is preferably present therein in amounts up to about byweight thereof and preferably as the concentrated acid. Suitable organicacids utilizable in the treating agent in- ,clude the mono-, anddicarboxylic acids such as acetic acid, propionic acid, succinic acid,tartaric acid'and others. Acids of the fatty acid series havingionization constants less than 1X1 are preferred, formic and aceticacids being especially preferred in the treatment of aluminacontainingcomposites by means of the present invention. Acids having higherdissociation constants including such mineralacids as hydrochloric,sulfuric, phosphoric, and hydrobromic acid and such organic acids asmono-, diand trichloroacetic acids, oxalic acid, etc. may be added tothe weaker organic acid forming the basic aluminum acid salt thereof inamounts up to about 10% by weight thereof, preferably up to about 5% byweight, particularly when the acid treating reagent is utilized toeffect reactivation of spent alumina-containing catalyst composites.These mineral and strong organic acids arenot equivalent in theireffectiveness, and hydrochloric acid is usually preferred. The amount ofthe alumina component removed from the alumina-containing compositedepends upon the period of treatment and is directly correlated with theconcentration and amount of the mineral acid or strong organic acidcontained in the acidic reagent; the reagent is therefore prepared withsuch factor in consideration, depending upon the amount of alumina it isdesired'to remove from the catalyst composite subjected to treatment.

In accordance with the present process, the alumina-containing compositeis treated with the acidic reagent at temperatures of from about 150? toabout 300 0., preferably from about 180 to about 250 C. to effect theformation of the aluminum salt of the organic acid component of thetreating reagent. At these temperatures, the pressure is maintainedsufficiently superat- 'mosphericto provide essentially liquid phaseconditions in the reactor. The treatment of the composite at theseconditions with the acid treating reagent results in the formation of analuminum salt of the acid or acids utilized in the reagent. Thetreatment may also convert certain foreign components of the catalyticcomposite, such as the oxides of iron, calcium, sodium, etc., to solublesalts which are removed by draining the excess of the acidic reagentfrom the treated catalyst composite following the treatment. Thealuminum salt of the organic acid, however, is substantially insolublein the organic acid treating reagent and is thus left in the body of thecatalyst particle. Following the initial treatment with the acidicreagent, the excess of the latter may be withdrawn from .the reactionmixture or water may be added directly thereto without withdrawing theexcess .of the reagent. It is generally preferred, how? ever; toremove-the=excess reagent' and addiwa t'er-to the treated 'catalystcompositefor the sub sequent hydroly-tic treatment: Hydrolysis ot the.organie aluminum salt retained on the catalyst particle is effected byheating thetreated cat-:-

alyst with waterat' a temperature above about 100 0., preferably fromabout-150 tdabout. 250 C., preferably maintaining:superatmospheric.pressure in the hydrolytic reactor: for. thexpure pose of" maintainingthe water inc. substantially. liquid phase. Thehydrolyzed?prodUctisxthereafter removed; for example,'..by-filtrationzor decantation, andv dried to-uform1 one; modification ofthe final catalystproductzz. The. acid-i treated catalyst may.-alternativelywbe heated to: the .indicated temperatures by passingsuperheated steam over the particles or by pressurizingrthe. same withsteam in a pressure autoclave-1,

Following. the. hydrolytic: stage: of the: present treatment, the .driedtreated :catalystit composites. may be calcined at temperaturesoff-from. about 35:09 to about 850? G2,. depending: upon: the;particular: hydrocarbon conversion: processin; which the: catalyst;composite isv utilized. Calcination off the treated catalyst. is:generally, employed for activating. alumina-silica; aluminaezirconia,and othercatalyst composites; to develop optimum activity for theirsubsequent use in hydrocarbon conversion reactions.

The present invention will: be; described? in greaterdetail;,withreferenceto specific embodiments of thezinventioniirrthefollowingiexamples, although: theseare not. intended to. limit thegenerally broad scope of: the; invention in strict accordance therewith;

EXAMPLE I:

The following: experiment was; run to indicate that. even a. freshlyprepared. sampleof silicaalumina catalystmaybe: improved by means .ofthe. present: treatment; In this experiment, a sample of silica-aluminacatalyst containing approximately: l1;1%' alumina, preparedby-precipitation of aluminum hydroxideg-on; a silicagel sphere followedby dryingand calcination at approximately 550 C. was utilized. Thiscatalyst has thefollowing properties when subjected to the testsindicated...

TABnmI Freshly'prepared'silica-alumina catalyst Average bulk density,grams/cc. 0.59 Volume percent activity 1 49 Weight percent activity 1 42H2/CH4 2 ratio produced on test in a, standard cracking procedure 2.0

1 The ability of the catalyst to catalytically crack hydrocarbons isspecified as its volume percent activity (when the volume or theconverted product is considered as basis) or as its weight percentactivity (when the weight of converted product is considered as basis).A Mid-Continent gas oil fraction having an API gravity of 31.4 and aninitial boiling point of 65 F. was passed over a solid bed of thecatalyst contained in a furnace maintained at a temperature of about 932F. at a space velocity of said gas oil of approximately 4 volumes pervolume of catalyst per hour. he liquid hydrocarbon product boiling at atemperature above about 400 F. was condensed in a receiver and thegaseous fraction together with the condensible gases boil ng at atemperature below about 400 F were collected in a separate receiver.whether the volume or weight basis of utilized the volume or weight oftotal product (consisting of 400 F. end-point gasoline plus uncondensedgas) divided by the amount of oil charged and the result multiplied by100 provides a value designated as the respective weight percent orvolume percent "activity of the catalyst.

The ratio of hydrogen to methane produced indicates the efficiency ofthe composite as a cracking catalyst, a high ratio of hydrogenindicating a great deal of undesirable dehydrogenation of the chargingstock and a low ratio (high CH indicating greater efliciency as acracking catalyst.

Depending upon computation is gamers:

' The freshly prepared. silicasa'lumina catalyst was treated withglacial acetic :acict: in accordancewith the. following experiments 75;grams-ofthe catalyst was heated with i grams of the acetic acid at 200C." for-' 6 hours-.iinia rotating: pressure. autoclave. followed. byfiltering the treated catalyst from: the 1 excess acid; wash: inghwith 1water. and drying: the: treated. composite; at 145' C.'- fon3 hours; Thetreated catalyst had. an average lbulkadensity of 0.44; a.volumetpercent. aotivity rof .36, a; weightperc'enti. activity. of; 41,and when. testedafor its; effectiveness inLcatalyt-P ically cracking agas oil charging: stock, the product contained aLH2/CH4 ratio of 114.

Aa sampleiof the. glacial acetic acid treated; catalyst. wassubjectedito hydrolysis by heating; 40 grams ofzthe vcataiystzwithalfiOgrams.of water atS1180'frC. for=.6 .h'oursin arotatingpressureiautoe clave; followed by. drying the treatediproducti at:145?"- CI. The recovered icatalystz has an: average bulk density of0.57. and. when tested in accordance with a standard catalytic crackingprocedure; has a volumepercent activity of 53; a weight percent activityof 46; and the gaseous product contained a I-I2/CH4'ratio of 116.

The above results indicate that eveninthezcase' of afreshlypreparedcatalyst, the activity-=of the catalyst and itsefficiencyin yieldingthedesired cracked products is increased lay-the present acidtreatment followed by'the' hydrolytio treatment; The results furtherindicate that: the density of thecatalyst may be reducedb'ythe-successive stages of treatment herein providedi EXAMPLEI. III

A, sample of spent. silica-alumina. cracking catalyst which had; become.deactivated by con:- tinued use in' a hydrocarbon cracking reaction was:treated in accordance with the present processdnithe followingexperiment; The spent catalyst, which was black; becauseof thedepositionof carbon on-itssurface; during its use as a crackingcatalyst, had'an average bulk density of 0.70,.its weightpercentactivity was 23 andin testing'rits cracking ability bymeanssoftheastandardprocedure outlined in footnote. (1) of Example I,was; relativelylow'as indicated by a hydrogen to methane ratio of 4.6 inthe productsof-thecra-cke ing: test... The spent catalyst was treatedwith glacialgacetic acid at200 C. for- 6; hours. fol-. lowed by; drying;thetreated; catalyst: separated from the excess of acetic acid. It hadan average bulk density of 0.32, a weight percent activity of 31 andproduced a product in which the hydrogen to methane ratio was 1.8.Hydrolytic treatment of the acid treated catalyst by heating the samewith water at 180 a catalyst having an average bulk density of 0.57, aweight percent activity of 32 and, when tested by means of the standardgas oil cracking test, produced a product in which the hydrogen tomethane ratio was 3.4.

These results indicate that by means of the present method of treatment,the density of the spent silica-alumina cracking catalyst may bedecreased, its weight percent activity markedly increased and itsefiiciency as a cracking catalyst greatly increased as indicated by thelower hydrogen to methane ratio in the products of the cracking reactionutilizing the treated catalyst as compared with the spent catalystinitially charged.

EXAMPLE III The spent silica-alumina cracking catalyst of Example IIhaving the same average bulk densi- C. for 6 hours yielded I ty, weightpercent activity and cracking efficiency was treated in the followingexperiment with-5a mixture of'acids consisting of a Epredominant.

proportion of glacial acidic acid and-*a-minor proportion of'concentrated hydrochloric .acid;

'75 grams of the catalyst was heated with a-mixa ture containing 150grams :of glacial acetic-acid" and 5 gramsofconcentrated,hydrochloric;acidj, at 200 C. for 6 hours ina rotatingpressure auto-.- claver The treated catalystiwas-filteredafrom.

EXAMPLE IV The spent silica-alumina cracking catalyst utilized inExample III and having the same cracking efiiciency as indicated by theproportion of hydrogen to methane in the products recovered in astandard cracking test utilizing the catalyst, was treated with amixture of dichloroacetic acid and glacial acetic acid in accordancewith the following experiment. .75 grams of the spent catalystwascharged into a rotating pressure autoclave with 150 grams of glacialacetic acid and grams of dichloroacetic acid wherein itwasheated at 200C. for 6 hours. The separated catalyst following the treatment, waswashed with water and heated with 150 grams of water at 180 C. for 6hours. The recovered catalyst dried at 145 C. for 3 hours, had anaverage bulk density of 0.52, a weight percent activity of 36 and whentested in accordance with the standard gas oil cracking test, produced aproduct containing a ratio of hydrogen to methane of 1.1, as compared tothe same ratio for the spent untreated catalyst of 4.6. I claim as myinvention:

1. A process for improving the physical and catalytic properties of analumina-containing mineral composite which comprises heatingsaidcomposite with an acidic reagent containing a major proportion of anorganic acid having a dissociation constant of less than 1X10? at'atemperature of frcm-aboutisfl" to about 300 (3.. undersuificientpressure'to maintain said reagent: in substantially liquid phase, said organicacid being of a concentration and amount suflicient to'convert-asubstantial portion, at least, of'the alumina into a basic aluminum saltof said acid, and thereafter'treating the resulting composite withwater-at a temperature above C. under 'suiiicient pressure to maintainthe water in substantially-liquid phase whereby to hydrolyze saidaluminum salt.

'2. The process of claim 1 further characterized in that the saidcomposite is a spent alumina-containing hydrocarbon conversion catalyst;

3. The process of claim 1 further characterized in that said acidicreagent comprises glacial acetic acid and up to 10%. by weight ofdichloroacetic acid.

' 4." The process of claim 1 further characterized in that said acidicreagent'contains upto about 10% by weight of a mineral acid.

5. The process of claim liurther characterized in' that-said acidicreagent comprises acetic acid containing at least %by weight of aceticacid.

6. The process ofclaim'l further characterized in'that said acidicreagent is a mixture of acetic acid and up toi 10% by weight ofhydrochloric acid; .7 v.

7. The process of claim 1 further characterized in that saidalumina-containing mineral composite is a silica-alumina composite.

8. The process of claim 1 further characterized in that said aluminaco'ntaining mineral composite is heated with said acidic reagent at atemperature of from about to about 250 C;

9. The process of claim 1' further characterized in that said resultingcomposite following the treatmentiof the'composite with theacidicreagent is heated with water at atemperatureof from about 150 toabout 250 C.

' LOUIS SCHMERLING;

References Cited in the file of'this patent- I UNI rEp STATES PATENTSName Number I .Date 2,162,202 Fuchs June. .13, .1939 2,180,576 Baylis'etal. NOV. 21, .1939 2,246,900 Schulze et 9.1. June 24, 1941 2,380,731Drake tfal. July 31, 1945 2,477,664 Shaber Aug; 2,-l949

1. A PROCESS FOR IMPROVING THE PHYSICAL AND CATALYTIC PROPERTIES OF ANALUMINA-CONTAINING MINERAL COMPOSITE WHICH COMPRISES HEATING SAIDCOMPOSITE WITH AN ACIDIC REAGENT CONTAINING A MAJOR PROPORTION OF ANORGANIC ACID HAVING A DISSOCIATION CONSTANT OF LESS THAN 1X10-3 AT ATEMPERATURE OF FROM ABOUT 150* TO ABOUT 300* C. UNDER SUFFICIENTPRESSURE TO MAINTAIN SAID REAGENT IN SUBSTANTIALLY LIQUID PHASE, SAIDORGANIC ACID BEING OF A CONCENTRATION AND AMOUNT SUFFICIENT TO CONVERT ASUBSTANTIAL PORTION, AT LEAST OF THE ALUMINA INTO A BASIC ALUMINUM SALTOF SAID ACID, AND THEREAFTER TREATING THE RESULTING COMPOSITION WITHWATER AT A TEMPERATURE ABOVE 100* C. UNDER SUFFICIENT PRESSURE TOMAINTAIN THE WATER IN SUBSTANTIALLY LIQUID PHASE WHEREBY TO HYDROLYZESAID ALUMINUM SALT.